Brisbane mother-of-three Rinabel Tiglao once posed for a happy snap inside the black ute before falling from the same vehicle in a bizarre road death.

Police say it is not clear how or why the 44-year-old fell from the Nissan Navara dual cab as it travelled up to 100km/h on an unsealed section of road at Middlemount, in central Queensland, just after midnight on December 31.